Why is my RSpec not loading Devise::Test::ControllerHelpers?

I'm using Rails 5, and Devise 3.5.1.

Going through a nice (older) book about creating/testing an API, which uses Devise authentication. It was written before Rails 5, so I chose not to use the new api-only version.

Here's my test...

#/spec/controllers/api/v1/users_controller_spec.rb    

require 'rails_helper'

describe Api::V1::UsersController, :type => :controller do
    before(:each) { request.headers['Accept'] = "application/vnd.marketplace.v1" }
    describe "GET #show" do
        before(:each) do
            @user = FactoryGirl.create :user
            get :show, params: {id: @user.id}, format: :json
        end
        it "returns the information about a reporter on a hash" do
            user_response = JSON.parse(response.body, symbolize_names: true)
            expect(user_response[:email]).to eql @user.email
        end
        it { should respond_with 200 }
    end
end

And here's a completely unexpected RSpec error

Devise::MissingWarden:
       Devise could not find the `Warden::Proxy` instance on your request environment.
       Make sure that your application is loading Devise and Warden as expected and that the `Warden::Manager` middleware is present in your middleware stack.
       If you are seeing this on one of your tests, ensure that your tests are either executing the Rails middleware stack or that your tests are using the `Devise::Test::ControllerHelpers` module to inject the `request.env['warden']` object for you.

So I go here - http://www.rubydoc.info/gems/devise/Devise/Test/ControllerHelpers

and tried this -> include Devise::Test::ControllerHelpers

which didn't help because the file controller_helpers.rb is nowhere in my project

What did I miss here?

Thanks

You could add the following to your rails_helper:

RSpec.configure do |config|
  config.include Devise::Test::ControllerHelpers, type: :controller
end

This will include Devise::Test::ControllerHelpers module in all :controller specs.